Just what does that mean? (girls, help)?

just started whith a girl I've been talking with for a long time and lst night she grabbed my head, kissed me and holded me real thight. I said to myself ''uu-haaa'' but when I wanted to make eye contact she refused to look at me and pressed her face to my chest...not crying, not sighing...just like that. I asked her why and she said ''just because''.